JP3433686B2 - Surface coated cemented carbide cutting tool with a hard coating layer that exhibits excellent chipping resistance - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vertically-grown titanium carbonitride layer (hereinafter referred to as l-type) constituting a hard coating layer.
(Shown by TiCN) has a much better chipping resistance. Even when intermittent cutting of steel or cast iron is performed at high speed and under heavy cutting conditions such as high cutting and high feed, chipping ( The present invention relates to a cutting tool made of a surface-coated cemented carbide (hereinafter referred to as a coated cemented carbide tool) that exhibits excellent cutting performance over a long period of time without occurrence of minute chipping or the like. 2. Description of the Related Art Conventionally, generally, a tungsten carbide-based cemented carbide substrate (hereinafter referred to as a cemented carbide substrate) has, on the surface thereof, (a) an average layer thickness of 0.1 to 5 μm and a granular crystal structure. Having titanium carbide (hereinafter referred to as TiC)
Layer, titanium nitride (hereinafter also shown as TiN) layer, titanium carbonitride (hereinafter shown as TiCN) layer, titanium oxide (hereinafter shown as Ti ₂ O ₃ ) layer, titanium carbonate (hereinafter shown as Ti)
A) a Ti compound layer composed of one or more of a CO layer, a titanium oxynitride (hereinafter, shown as TiNO) layer, and a titanium oxycarbonitride (hereinafter, shown as TiCNO) layer; An l-TiCN layer having an average layer thickness of １５15 μm, (c) aluminum oxide having an average layer thickness of 0.5 to 8 μm and a granular crystal structure (hereinafter, referred to as Al ₂ O ₃ )
Layer, the hard coating layer composed of the above (a) to (c)
A coated carbide tool formed by chemical vapor deposition with a total average layer thickness of 25 μm is known, and it is also known that this coated carbide tool is used for continuous cutting or interrupted cutting of steel, cast iron, or the like. It is also well known that, generally, those having an α-type crystal structure, those having a κ-type crystal structure, and the like are widely and practically used as the Al ₂ O ₃ layer constituting the hard coating layer of the coated carbide tool. Further, the above-mentioned 1-TiCN layer is formed, for example, in JP-A-6-8010 or JP-A-7-32880.
No. 8 and the like, and formed by chemical vapor deposition in a normal temperature range of 700 to 950 ° C. using a mixed gas containing an organic carbonitride as a reaction gas in a normal chemical vapor deposition apparatus. It is. On the other hand, in recent years, there has been a strong demand for labor saving and energy saving for cutting, and accordingly, cutting has been accelerated and heavy cutting such as high cutting and high feed has been performed. However, in the above-described conventional coated cemented carbide tool, since the l-TiCN layer constituting the hard coating layer has relatively good toughness, the hard coating layer also has good toughness. In high-speed cutting, the cutting edge does not generate chipping or the like and exhibits excellent cutting performance, but the cutting conditions become more severe, and intermittent cutting is performed at high speed with high cutting and high feed rates. In the case of heavy cutting conditions such as such, chipping does not occur unavoidably because it does not yet have sufficient toughness, and the service life can be reached in a relatively short time at present. is there . [0004] Therefore, the present inventors have proposed:
From the above viewpoint, the inventors focused on the l-TiCN layer constituting the hard coating layer of the conventional coated cemented carbide tool, and conducted a study to further improve the toughness of the l-TiCN layer.
When forming the N layer by vapor deposition, it is a constituent component in the reaction gas.
CH ₃ CN, or CH ₃ CN and CH ₄ By changing the content ratio of steplessly or stepwise over time,
The l-TiCN layer is provided with a concentration gradient in which the C component is low and the N component is high along the layer thickness from the lower surface to the upper surface of the l-TiCN layer. When expressed by the formula: TiC _1-x N _x , the upper surface portion satisfies x: 0.65 to 0.95, and the lower surface portion satisfies x: 0.05 to 0.35 by atomic ratio ( In this case, the concentration change from the lower surface portion to the upper surface portion of C and N changes steplessly or stepwise, and the resulting l-TiCN layer (hereinafter referred to as concentration gradient l-TiCN layer) is obtained. Is C from the lower surface to the upper surface.
And N have a higher toughness than a conventional conventional 1-TiCN layer having no concentration change, and therefore, the coated carbide tool in which the concentration gradient 1-TiCN layer constitutes a hard coating layer Since the hard coating layer itself becomes more excellent toughness due to the concentration gradient 1-TiCN layer, interrupted cutting is performed at high speed and heavy cutting. The research results show that excellent cutting performance can be achieved without chipping. The present invention has been made on the basis of the above-mentioned research results, and is characterized in that (a) TiC having an average layer thickness of 0.1 to 5 μm and a granular crystal structure, Layer, TiN layer, TiCN layer, T
i ₂ O ₃ layer, TiCO layer, TiNO layer, and TiCN
A Ti compound layer composed of one or more of O layers; (b) having an average layer thickness of 2 to 15 μm ,
A component CH ₃ CN or free CH ₃ CN and CH _4,
Articles in which the percentage changes steplessly or stepwise over time
The upper surface and the lower surface have the composition formula: Ti
When expressed as C _1-x N _x , the atomic ratio of the upper surface portion satisfies x: 0.65 to 0.95, and the lower surface portion satisfies x: 0.05 to 0.35. A concentration gradient 1-TiCN layer having a concentration gradient of N in the thickness direction and in which the concentrations of C and N change steplessly or stepwise; (c) an average layer thickness of 0.5 to 8 μm and a granular crystal structure; the Al ₂ O ₃ layer, formed by chemical vapor deposition or (a) ~ hard layer composed of a (c) the whole average layer thickness of 3～25Myuemu, exhibits chipping resistance of the hard coating layer has excellent having The coated carbide tool has features. The composition formula of the concentration gradient 1-TiCN layer constituting the hard coating layer of the coated cemented carbide tool of the present invention: TiC
In _1-x N _x, the x value of the upper surface portion from 0.65 to 0.
95, desirably 0.70 to 0.85, and the x value of the lower surface portion is 0.05 to 0.35, preferably 0.15 to 0.30, because the x value of the upper surface portion is less than 0.65. Or the x value of the lower surface portion exceeds 0.35, the C in the layer thickness direction
And the concentration gradient of N becomes small, so that a further improvement in toughness cannot be obtained. As a result, the hard coating layer cannot have a desired excellent chipping resistance, and the x value of the upper surface is 0.95. When the x value of the lower surface portion is less than 0.05, the concentration gradient of C and N becomes too large, and it becomes difficult to secure a vertically elongated crystal structure, and the toughness is remarkably reduced. Is inevitable, and as a result, chipping is likely to occur. Similarly, each of the Ti compound layers constituting the hard coating layer has an effect of improving interlayer adhesion between the constituent layers. Therefore, if the average layer thickness is less than 0.1 μm, a desired excellent interlayer thickness is obtained. Since the adhesion cannot be ensured, and if the average layer thickness exceeds 5 μm, the progress of wear of the hard coating layer is promoted, so the average layer thickness is set to 0.1 to 5 μm. Similarly, the Al ₂ O ₃ layer has an effect of improving the wear resistance of the hard coating layer,
If the average layer thickness is less than 0.5 μm, the desired excellent wear resistance cannot be secured, while the average layer thickness is 8 μm.
If the thickness exceeds μm, chipping is likely to occur on the cutting edge. Therefore, the average layer thickness is set to 0.5 to 8 μm. Furthermore, the concentration gradient 1-TiCN layer has the effect of further improving the chipping resistance of the hard coating layer as described above, but if the average layer thickness is less than 2 μm, the desired effect of improving the chipping resistance can be obtained. The average layer thickness is 15μ
When m exceeds m, abrasion resistance rapidly decreases, so the average layer thickness is set to 2 to 15 μm. In addition, the reason why the total average layer thickness of the hard coating layer is set to 3 to 25 μm is that if the average layer thickness is less than 3 μm, desired wear resistance cannot be secured, while the average layer thickness exceeds 25 μm. This is because the chipping and chipping of the cutting edge are likely to occur. Next, the coated carbide tool of the present invention will be described in detail with reference to examples. As raw material powder, WC powder having an average particle diameter of 1.5 μm, (Ti, W) CN of the same 1.2 μm (the same in weight ratio, hereinafter,
N / WC = 24/20/56) powder, 1.3 μm (Ta, Nb) C (TaC / NbC = 90/10) powder, 1 μm Cr ₃ C ₂ powder, 1.2 μm VC powder , And 1.2 μm of the same Co powder were prepared, and these raw material powders were mixed in the compounding composition shown in Table 1, wet-mixed in a ball mill for 72 hours, and dried.
The green compact is press-formed into a green compact having a shape conforming to SO standard SNMG120408, and the green compact is heated to a predetermined temperature within a range of 1400 to 1460 ° C. in a vacuum atmosphere of 10 ⁻³ torr.
Carbide substrate A ~
F were each manufactured. Then, the surfaces of these super-hard substrates A to F are subjected to honing processing, and a conventional chemical vapor deposition apparatus is used. Have a uniform composition with no change in the concentration of the constituent components from the lower surface to the upper surface of the layer.
Under the conditions shown in (4), a hard coating layer having the composition shown in Tables 4 and 5 and the target layer thickness (flank of the cutting edge) was formed under the conditions shown in Tables 4 and 5. The coated carbide tools 1 to 10 of the present invention and the conventionally coated carbide tools 1 to 10 were respectively manufactured. In Table 4, for example, “l-TiCN (A) [5 steps] l-TiC
N (4.3) ”is the“ lower surface part / l-TiCN ”in Table 3.
(A) (x: 0.05) ”to the reaction gas composition of“ upper surface portion / l-TiCN (x: 0.75) ”to CH ₃ CN in the reaction gas, or CH ₃ CN and CH _Four
Shows the case where a concentration gradient of 1-TiCN layer is formed with a target layer thickness of 4.3 μm by changing the content ratio of 5 steps over time, and “l-TiCN (a) [continuous] l-
“TiCN (3.8)” is “lower surface part / l-TiCN”
(A) From the reaction gas composition of (x: 0.10) ”to the reaction gas composition of“ upper surface part / l-TiCN (x: 0.65) ”, CH ₃ CN in the reaction gas, or CH ₃ CN and CH _Four
Is a case where the concentration gradient of the 1-TiCN layer is formed with a target layer thickness of 3.8 μm by continuously changing the content ratio over time. The coated carbide tool 1 of the present invention obtained as a result
The x value of the upper surface portion and the lower surface portion of the concentration gradient l-TiCN layer constituting the hard coating layer of Nos. To 10 were measured using an Auger spectrometer inside 0.2 μm from each surface. The value corresponding to the target value shown is shown. In addition, the constituent layers constituting the hard coating layer also showed substantially the same average layer thickness as the target layer thickness. Next, the coated carbide tools 1 to 10 according to the present invention will be described.
And conventional coated carbide tools 1 to 10, Work material: SCM440 round bar with four longitudinal grooves at regular intervals in the longitudinal direction, Cutting speed: 300 m / min. Infeed: 5.0 mm Feed: 0.3 mm / rev. , Cutting time: 15 minutes, Dry high-speed high-cut intermittent cutting test of alloy steel under the following conditions:
Work material: round bar with four longitudinal grooves at equal intervals in the longitudinal direction of SCM440, cutting speed: 300 m / min. Infeed: 1.5 mm Feed: 0.6 mm / rev. , Cutting time: 10 minutes, Dry high-speed high feed intermittent cutting test of alloy steel under the conditions of
In each cutting test, the maximum flank wear width of the cutting edge was measured. Table 6 shows the measurement results. [Table 1] [Table 2] [Table 3] [Table 4] [Table 5] [Table 6] From the results shown in Tables 4 to 6, the coated carbide tools 1 to 10 according to the present invention in which the concentration gradient 1-TiCN layer is present in the hard coating layer are all the same. TiCN
Since the hard coating layer has excellent toughness due to the layer, chipping is performed on the cutting edge even under extremely severe cutting conditions where interrupted cutting of steel is performed at high speed and high cutting and high feed conditions. In the conventional coated carbide tools 1 to 10 having no concentration gradient in C and N of the l-TiCN layer constituting the hard coating layer, while exhibiting excellent cutting performance without occurrence of Under the cutting conditions, it is clear that chipping occurs on the cutting edge due to insufficient toughness of the hard coating layer, and the service life is reached in a relatively short time. As described above, in the coated carbide tool of the present invention, the hard coating layer constituting the tool has excellent chipping resistance, so that, for example, continuous cutting or interrupted cutting under ordinary conditions such as steel or cast iron is of course possible. In particular, it can exhibit excellent cutting performance over a long period of time even under extremely severe conditions, in which interrupted cutting is performed at high speed and under heavy cutting conditions. It can respond satisfactorily to the conversion.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Masayuki Miichi 1511 Furamagi, Ishishita-cho, Yuki-gun, Ibaraki Pref. Mitsubishi Materials Corporation Tsukuba Works (56) References JP-A-7-34250 (JP, A) JP-A-8-187605 (JP, A) JP-A-9-234605 (JP, A) JP-A-10-244405 (JP, A) JP-A-4-240005 (JP, A) JP-A-7-331443 ( JP, A) JP-A-8-1408 (JP, A) JP-A-6-8010 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B23B 27/14 C23C 16/30

Claims (1)

(57) [Claims 1] A titanium carbide layer having a mean layer thickness of 0.1 to 5 µm and a granular crystal structure in each case on the surface of a tungsten carbide based cemented carbide substrate, A titanium compound layer comprising one or more of a titanium nitride layer, a titanium carbonitride layer, a titanium oxide layer, a titanium carbonate layer, a titanium oxynitride layer, and a titanium carbonitride oxide layer, (b) 2 to 15 μm The composition of the reaction gas
A component CH ₃ CN or free CH ₃ CN and CH _4,
Articles in which the percentage changes steplessly or stepwise over time
The upper surface and the lower surface have the composition formula: Ti
When expressed as C _1-x N _x , the atomic ratio of the upper surface portion satisfies x: 0.65 to 0.95, and the lower surface portion satisfies x: 0.05 to 0.35. A titanium carbonitride layer having a vertically elongated crystal structure having a concentration gradient of N in the thickness direction and the C and N concentrations changing steplessly or stepwise; (c) an average layer thickness of 0.5 to 8 μm and granularity; An aluminum oxide layer having a crystal structure, 3 to 25 hard coating layers composed of the above (a) to (c)
A cutting tool made of a surface-coated cemented carbide that exhibits excellent chipping resistance, characterized in that the hard coating layer is characterized by being chemically deposited with a total average layer thickness of μm.